Devices have been suggested by the prior art as seen by U.S. Pat. No. 3,544,235 to provide pressure control of a pump discharge of a fire truck pumper using pump pressure to provide engine throttle control to maintain pressure and prevent engine overspeed. It has even been suggested that the pump pressure may be biased against a desired fluid pressure for the control of still another fluid pressure supply that is used to control engine rpm as seen in U.S. Pat. No. 2,642,805. It has even been suggested by the prior art in U.S. Pat. No. 2,570,727 that an electrical control circuit be interposed in a pump governor system to activate and maintain governor control whenever there is being developed by the pump discharge above atmosphere.